Introduction

What Tanso is and who it’s for

Tanso is an open-source monetization engine for B2B AI products — built for teams that sell credits or usage and whose inference costs are big enough that margin per customer is a real question.

Every metered event carries its cost: input/output tokens, model, provider, and what that usage cost you — alongside what you billed for it. Billing tools meter usage but don’t know your costs; observability tools know your costs but don’t bill. Tanso does both in one ledger, so you can see margin per customer, per feature, per model.

The same ledger enforces in real time: entitlement checks, usage caps, and credit limits are applied when the event is ingested, not reconciled at invoice time. Billing state lives in Tanso — Stripe is the payment adapter, not the source of truth.

The model

You define your pricing once, and everything else derives from it:

Object	What it is
Feature	A single capability you sell — api-calls, seats, export
Plan	A bundle of features with a base price and billing interval
Rule	How a feature behaves in a plan: flat, usage-based, or graduated pricing, plus optional credit backing
Customer	Your customer, keyed by your ID (customerReferenceId) — no ID sync
Subscription	A customer on a plan, with period tracking and proration
Event	One unit of usage, idempotent, carrying units, cost, and revenue
Entitlement	The materialized answer to “can this customer use this feature right now?”
Credit pool	Prepaid balance with grants, FIFO draw-down, expiry, and an append-only transaction ledger

The integration loop

Three calls from your backend:

1. Check an entitlement before serving a request.
2. Serve the request.
3. Report a usage event after.

Tanso enforces limits at ingestion, rolls usage into invoices at cycle close, syncs Stripe when connected, and computes margin from the costs you stamp on events.

Next steps

• Quickstart — running with seeded data in about five minutes
• Billing lifecycle — from empty database to first revenue, every call spelled out
• Self-hosting — configuration and production notes